All kind of luminaires are known in the art. Some examples, chosen out of the large number of different types of luminaires, are given below.
WO2009144668 describes an illumination device comprising a lighting unit. The lighting unit comprises a light source and a substantially flat collimator, arranged to collimate light source light. The collimator has an entrance window, an edge window, a top collimator surface, a bottom collimator surface, a first collimating side edge and a second collimating side edge. The lighting unit has an optical axis. One or more of the top collimator surface, the bottom collimator surface, the first collimating side edge and the second collimating side edge comprise n*½ grooves, wherein n is a positive integer number, and wherein the grooves independently have a longitudinal axis having a groove direction angle (ω) with the optical axis (O) ≧0° and <90°. Especially, one or more of the top collimator surface and the bottom collimator surface comprise a plurality of grooves, which may virtually converge at a position coinciding with the light source.
WO2007069185 describes a lamp assembly for illuminating a surface comprising a chamber accommodating a plurality of light-emitting diodes capable of emitting visible light. The lamp assembly comprises diffusing means capable of diffusing said visible light of said light-emitting diodes to produce diffuse light, and said chamber further accommodates collimation means arranged to collimate at least a portion of said diffused light for illuminating said surface. The lamp assembly is especially suitable for ambiance and atmosphere lighting applications.